At half-time of England's World Cup semifinal against Croatia in July, Gareth Southgate's side were cruising. A goal up from the fifth minute courtesy of Kieran Trippier's free-kick, England had dominated, enjoyed further chances, and should have been out of sight.

Instead, they couldn't sustain their performance. Croatia rallied, enforced long spells of pressure, equalised, continued to dominate, and eventually scored an extra-time winner.

England's major problem wasn't about fitness, a constant explanation for their underperformance after half-time in major international tournaments. It wasn't even necessarily about technical inferiority. No, instead it was about tactics.

England continued to play in a solid 5-3-2 system, with Croatia's wingers forcing back their wing-backs, leaving huge amounts of space down the flanks. Luka Modric and Ivan Rakitic switched play from flank to flank, and England's three-man midfield couldn't work across the pitch laterally to close down. Right-back Sime Vrsaljko, Croatia's best performer in their quarterfinal win over Russia and an obvious threat, provided the crucial cross for Ivan Perisic's equaliser.

Southgate had around 20 minutes to formulate an alternative system to shut down Croatia's area of strength. The most obvious would have involved removing one of the strikers and introducing a makeshift left-winger, changing formation only slightly and occupying Vrsaljko. But the manager persisted with the same system, England couldn't cope down the flanks, and their the opportunity to reach the World Cup final was gone.

Southgate had two months to address this shortcoming ahead of England's next fixture, the 2-1 defeat to Spain.

On Saturday evening. England performed admirably in some respects and were unfortunate that Danny Welbeck's last-minute "goal" was disallowed for a questionable infringement when battling David De Gea for an aerial ball. But when England were being dominated throughout the first half, the same problem was obvious -- Spain's full-backs Dani Carvajal and Marcos Alonso were always free for a switch of play, with Jesse Lingard and Dele Alli, once again, forced to constantly sprint out towards the touchlines.

While 3-5-2 enjoyed a surge in popularity during Southgate's playing career, it's a formation rarely used in modern football. In part, that's because of the obvious weakness down the flanks, and while Southgate's use of the system has offered some benefits -- overlapping from wing-back and good combination play upfront -- it remains a surprise that England haven't formulated a gameplan to fight against the system's obvious shortcoming.

The lack of tactical variety has been startling, with the only notable change in shape coming in the second half of Tuesday's 1-0 victory over Switzerland. Even then it was minor, flipping the midfield triangle to play with two holding midfielders rather than one.

Switzerland coach Vladimir Petkovic had switched formation to a 3-5-2, or 3-5-1-1, of his own and England struggled to pass through the opposition. The upside from England's perspective was that they weren't overloaded down the flanks, with wing-back tracking wing-back. If Stephan Lichtsteiner and Ricardo Rodriguez had gone free, as would have happened had Switzerland stayed in a 4-2-3-1, we would have seen England suffer in the same fashion yet again.

In truth, few international sides boast full-backs impressive enough to force a tactical change, and England are slightly unfortunate that they've played three sides in a row boasting those as dangerous as Vrsaljko, Alonso, Carvajal and Rodriguez. But that doesn't mean they shouldn't have formulated a plan, and the next two matches are Nations League trips to Croatia and then Spain in October.

England have an issue down the flanks, but how can they solve it? Laurence Griffiths/Getty Images

So what's the solution? Well, the obvious way to provide extra width would be switching to a 5-4-1 system without possession, which is probably what Southgate should have done against Croatia in July. Lingard can shift into a right-sided midfield position without any problems; Alli can play alongside Jordan Henderson in the middle; any of Raheem Sterling, Danny Welbeck and Marcus Rashford would be comfortable dropping back to left-wing.

This doesn't necessarily need to happen from the outset, but when England are in a deep block, and facing long periods under sustained pressure, it's difficult to make a case for leaving two men up front.

That system becomes less desirable against a side like Spain, however, who boast a top-class deep-lying midfielder in Sergio Busquets. Southgate, understandably, asked Rashford to track Busquets on Saturday night, and leaving the Barcelona midfielder free would be a much greater crime than giving the full-backs too much space.

Therefore, Southgate might need to consider playing something of a hybrid system, and getting England to defend in a 4-4-1-1 rather than a 5-3-1-1. This shift between a three-man and four-man defence isn't simple, but it's something that, for example, Juventus often perform effectively.

Joe Gomez or Kyle Walker, England's right-sided centre-back, could move out to right-back and allow Trippier to push forward to become the right-sided midfielder. Alli could move out to left-sided midfield -- or Lingard could be used in that role -- and England would offer more balance and structure out wide, while also ensuring they aren't overrun in midfield.

The more dramatic alternative would be moving away from the three-man defence entirely, but Southgate acknowledges that he's blessed with the right defensive options to play that system. Besides, the unusual formation has caused opponents problems, and for the first time in a generation it feels like England boast a clear, obvious identity.

Southgate's elevation into a popular, respected manager whose dignity and eloquence helped rally the nation was perhaps the most enjoyable aspect of a memorable summer for the national side. His impact in a general sense has been hugely positive.

But while this is a new generation of players with a new atmosphere around it, England retain their old tactical shortcomings. Without a better gameplan next month, the games against Croatia and Spain could take on a familiar pattern.